A postdoctoral researcher, post-doctoral researcher or postdoctoral fellow is a person conducting research after the completion of their doctoral studies (typically a PhD) as part of a temporary appointment, usually in preparation for an academic faculty position. It is intended to further deepen expertise in a specialist subject, including integrating a team and acquiring novel skills and research methods. Postdoctoral research is often considered essential while advancing the scholarly mission of the host institution; it is expected to produce relevant publications in peer-reviewed academic journals. In some countries, postdoctoral research may lead to further formal qualifications or certification, while in other countries it does not.[2][3]

Postdoctoral research may be funded through an appointment with a salary or an appointment with a stipend or sponsorship award. Appointments for such a research position may be called postdoctoral research fellow, postdoctoral research associate or postdoctoral research assistant. Depending on the type of appointment, postdoctoral researchers may work independently or under the supervision of a principal investigator. However, a designated postdoctoral research appointment may also be taken up when other suitable positions are not available, rather than merely pursuing the deepening of scholarly experience. In many English-speaking countries, postdoctoral researchers are colloquially referred to as "postdocs".[4]

In the United Kingdom, 25% of doctors in the natural sciences continue to undertake postdoctoral research.[18]

Since the landmark ruling in the employment tribunal (Scotland) Ball vs Aberdeen University 2008 case (S/101486/08), researchers who have held successive fixed-term contracts for four years service are no longer temporary employees but are entitled to the open-ended contracts.[19]

In the US, a postdoctoral scholar is an individual holding a doctoral degree who is engaged in mentored research and/or scholarly training for the purpose of acquiring the professional skills needed to pursue a career path of his or her choosing.[2] Postdoctoral researchers play an important role in spearheading research activity in the US. The median salary of postdoctoral researchers is $42,000 a year for up to 5 years after receiving their doctoral degrees — 44% less than that of tenured positions.[20] The National Postdoctoral Association (NPA)[21] is a member-driven organization that provides a voice for postdoctoral scholars in the United States.

Postdoctoral research may be required for obtaining a tenure-track faculty position, especially at research-oriented institutions. Post-doctoral appointments that were traditionally optional have become mandatory in some fields as the degree of competition for tenure-track positions in academia has significantly increased over previous decades. In fact, the small supply of the professional positions in academia compared to the growing number of postdoctoral researchers makes it difficult to find tenure-track positions. In 2008, the proportion of postdoctoral researchers who got a tenure or tenure-track within 5 years after they received a doctoral degree was about 39%;[20] nearly 10% of postdoctoral researchers were still waiting for tenure-track positions over 40 in 2003.[22]

On the other hand, 85 percent of engineering doctoral degrees holder are likely to initially go into business or industry sector.[23] Under the circumstances, providing doctoral students as well as postdoctoral researchers with necessary skills for nonacademic positions has become one of the important roles for graduate schools and institutions. The America COMPETES Act recognized the importance of graduate student support for obtaining skills needed when they pursue nonacademic careers, and required National Science Foundation (NSF) to increase or decrease funding for the Integrative Graduate Education and Research Traineeship (IGERT) programs[24] at least at the same rate as it increases or decreases funding for the Graduate Research Fellowship program. IGERT has been providing Ph.D. graduate students with more interdisciplinary experience, broad based professional and technical skill, various training needed in nonacademic careers, off-campus internships and career information since 1998.

There are no comprehensive data of postdoctoral researchers in the US because of the less-organized survey and the difficulty in counting international postdoctoral researchers. The proportion of postdoctoral researchers on temporary visas reached 53.6% in 2010.[25]

In the US, life sciences have a greater share than other fields due to higher federal funding of life and medical science areas since mid 1990[citation needed]. One survey shows that 54% of postdoctoral researchers major in life sciences, whereas those who majored in physical science, mathematics, and engineering account for 28%.[26]

In 2010, postdoctoral researchers in California formed a union, UAW Local 5810 in order to secure better working conditions such as the right to file a complaint for alleged discrimination or sexual harassment through a formal grievance procedure.[27] In California, new postdoctoral appointments receive at least the NIH postdoctoral minimum salary ($39,264 in 2011) and many receive annual pay raises of 5-7% or more in accordance with the NIH’s Ruth L. Kirschstein National Research Service Awards (NRSA).[28]

Alternatively the Australian Research Council (ARC) provides Postdoctoral Fellowships. For example their Discovery Projects,[32] funds 3 year Fellowships, beginning in 2009, with A$61,399 p.a.[33] Furthermore, a mandatory superannuation payment of 11-17% is paid by Universities.[34]